I think they meant the "She's also one of the mafia leaders and she has 7 guardians to protect her, and Exidium is one of the 7. Every guardian including Exidium has elemental power and Exidium possess dark element" part...
I don't know if you've read Reborn, but Tsuna also has guardians to protect him, and they each have an element thing??;;
I forgot... OTLBut I agree, it's not much alike.
I wouldn't have thought so at all if someone didn't comment about it.